What Does U1103 Mean?
Similar to previous U1100-series codes, this indicates missing primary identification data from a network module. Represents another specific module communication failure on the J1850 SCP bus.
Common Causes
35%
Failed control module not transmitting on network bus
28%
Open circuit or high resistance in network bus wiring
22%
Loss of power or ground to affected module
12%
Corrosion or damage in module connector terminals
3%
Electromagnetic interference from aftermarket equipment
Diagnostic Steps
1
Step 1: Use scan tool to determine which module is not sending identification data to the network
2
Step 2: Check fuse panel for any blown fuses related to the non-communicating module
3
Step 3: Inspect the affected module's wiring harness and connector for visible damage or corrosion
4
Step 4: Measure network bus voltage and resistance; compare readings at DLC and at affected module connector
5
Step 5: Test power and ground circuits at the module; verify proper voltage and less than 0.5 ohms ground resistance
Estimated Repair Cost
$150 - $1,400
Parts + labor, varies by vehicle and location
Similar to previous U1100-series codes, this indicates missing primary identification data from a network module. Represents another specific module communication failure on the J1850 SCP bus.
The most common cause of U1103 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Failed control module not transmitting on network bus
Typical repair costs for U1103 range from $150 to $1,400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Functionality loss depends on which module is affected. May result in inoperative comfort systems or potentially critical safety systems requiring immediate diagnosis.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1103 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Communication Network
Difficulty
Type
Manufacturer
Recommended Tools
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